MANILA — Rescue workers in the Philippines began Sunday to bury landslide victims in a mass grave as the Red Cross said more than 1,000 people had probably died in the disaster.

The official death toll in the landslides, triggered when Typhoon Durian loosened the slopes of a volcano in the northern province of Albay, stood at 406 on Sunday, but officials warned that it would certainly climb and that there was little hope of finding more survivors.

"There are many unidentified bodies, there could be a lot more hidden below," Richard Gordon, the chairman of the Philippine National Red Cross, told The Associated Press. "Whole families may have been wiped out."

President Gloria Macapagal Arroyo declared a "state of national calamity" on Sunday to hasten the release of government funds for rescue and recovery efforts in the hardest hit areas in the Bicol region, a group of several provinces in the eastern Philippines that are frequently buffeted by typhoons.

Typhoon Durian slammed into the region on Thursday, bringing heavy rains and strong winds that destabilized the slopes of Mayon, the country's most active volcano. Most of those who were killed lived in villages near the foot of Mayon.

Mud and boulders cascaded down the mountain, crushing people in their path. Rescuers said many of those killed had been torn to pieces. Entire villages lay buried beneath thick, black volcanic sludge.

Gene Villareal, an Albay official involved in the rescue effort, said the mass grave was a necessary precaution.

"We opted to do this because we might have an epidemic, which could be expected because of the high number of evacuees and homeless," Villareal told The Associated Press.

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More than 40,000 people were displaced by the mudslides, according to official estimates.

Durian, one of the strongest typhoons to hit the country in years, knocked down phone towers and power lines, plunging the whole region into darkness. The storm destroyed an estimated 120,000 homes, uprooted trees and swept away vehicles.

More than 800,000 were affected by the typhoon, many stranded in their homes without electricity, food or water. Others were holed up in schools, churches and other temporary shelters across the Bicol region.

"Every corner of this province has been hit. It is a total devastation," said Fernando Gonzales, the governor of Albay. "Never before in the history have we seen water like this. Almost every residential area was flooded."

Although thousands of residents managed to flee to evacuation centers before the typhoons struck, many remained in their homes.